Adjustment portion of a headphone device



FIG. 1 is a perspective view of an adjustment portion of a headphone device showing my new design.

FIG. 2 is a front elevational view thereof.

FIG. 3 is a back elevational view thereof.

FIG. 4 is a first side elevational view thereof.

FIG. 5 is a second side elevational view thereof.

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines depict environment that forms no part of the claimed design. 

CLAIM The ornamental design for an adjustment portion of a headphone device, as shown and described. 